Magnetic tape write once overwrite protection

ABSTRACT

A magnetic tape cartridge, a recording system, and a magnetic tape drive are configured to, for example, guard against tampering with a write once overwrite protection pointer which allows a rewritable magnetic tape to be treated as write once. In one embodiment, the magnetic tape cartridge comprises a magnetic tape and a cartridge memory. The magnetic tape is configured to provide at least one overwrite protection pointer, the overwrite protection pointer identifying data to be protected from being overwritten; and the cartridge memory is configured to provide the at least one overwrite protection pointer, the overwrite protection pointer identifying magnetic tape data to be protected from being overwritten.

FIELD OF THE INVENTION

This invention relates to the utilization of rewritable magnetic tape aswrite once media, for example, known as write-once-read-many (“WORM”)media.

BACKGROUND OF THE INVENTION

Magnetic tape is typically a rewritable recording media, but may berendered as write once media by limiting overwrite of the media. Forexample, copending and coassigned U.S. Pat. No. 6,339,810, Basham etal., discusses treating data storage media as WORM by automaticallyadvancing a write append limiter as data is written, and preventingchanges to data occurring before the write append limiter.

SUMMARY OF THE INVENTION

In one embodiment, a magnetic tape cartridge is configured to guardagainst tampering with a write once overwrite protection pointer. Themagnetic tape cartridge comprises a magnetic tape and a cartridgememory. The magnetic tape provides at least one overwrite protectionpointer, the overwrite protection pointer identifying data to beprotected from being overwritten; and the cartridge memory provides theat least one overwrite protection pointer. The overwrite protectionpointer identifying magnetic tape data to be protected from beingoverwritten.

In another embodiment, a recording system for magnetic tape. Themagnetic tape mounted with respect to a magnetic tape cartridge having acartridge memory, comprises logic configured to record at least oneoverwrite protection pointer on the magnetic tape, the overwriteprotection pointer identifying data to be protected from beingoverwritten; and logic configured to provide the overwrite protectionpointer to the cartridge memory, the overwrite protection pointeridentifying magnetic tape data to be protected from being overwritten.

In another embodiment, a magnetic tape drive is configured to read andwrite information with respect to a magnetic tape mounted with respectto a magnetic tape cartridge having a cartridge memory. The magnetictape drive comprises at least one motor configured to move the magnetictape longitudinally; at least one read/write head configured to readfrom and to write to the magnetic tape while the magnetic tape is movedlongitudinally by the motor(s); at least one recording channelconfigured to operate the read/write head(s) to read from and to writeto the magnetic tape; a memory interface configured to communicate withrespect to the cartridge memory; and at least one control systemconfigured to operate the at least one recording channel to record atleast one overwrite protection pointer on the magnetic tape, theoverwrite protection pointer identifying data to be protected from beingoverwritten; and configured to operate the memory interface to providethe at least one overwrite protection pointer to the cartridge memory,the overwrite protection pointer identifying magnetic tape data to beprotected from being overwritten.

In a further embodiment, the magnetic tape overwrite protection pointerand the cartridge memory overwrite protection pointer, comprises aplurality of updateable overwrite protection pointers, the overwriteprotection pointers configured to be updated in a sequence.

For a fuller understanding of the present invention, reference should bemade to the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a magnetic tape cartridge with a magnetictape and a cartridge memory shown in phantom;

FIG. 2 is a block diagrammatic representation of a magnetic tape drivefor handling the magnetic tape cartridge of FIG. 1;

FIG. 3 is a diagrammatic representation of information provided on amagnetic tape, comprising beginning of tape information and a data set;

FIG. 4 is a diagrammatic representation of information provided in acartridge memory, including WORM information;

FIG. 5 is a diagrammatic representation of information related to anoverwrite protection pointer; and

FIG. 6 is a diagrammatic representation of information related to a datafile provided on a magnetic tape.

DETAILED DESCRIPTION OF THE INVENTION

This invention is described in preferred embodiments in the followingdescription with reference to the Figures, in which like numbersrepresent the same or similar elements. While this invention isdescribed in terms of the best mode for achieving this invention'sobjectives, it will be appreciated by those skilled in the art thatvariations may be accomplished in view of these teachings withoutdeviating from the spirit or scope of the invention.

Referring to FIG. 1, an example of a magnetic tape cartridge 10 in whichthe present invention may be employed is illustrated which comprises arewritable magnetic tape 11 wound on a hub 12 of reel 13, and acartridge memory 14. One example of a magnetic tape cartridge comprisesa cartridge based on LTO (Linear Tape Open) technology. The cartridgememory 14, for example, comprises a transponder having a contactlessinterface, which is retained in the cartridge 10, for example, by beingencapsulated by the cartridge when it is assembled, as is understood bythose of skill in the art. The illustrated magnetic tape cartridge is asingle reel cartridge. Magnetic tape cartridges may also comprise dualreel cartridges in which the tape is fed between reels of the cartridge.

Referring to FIG. 2, a magnetic tape drive 15 is illustrated. Oneexample of a magnetic tape drive in which the present invention may beemployed is the IBM 3580 Ultrium magnetic tape drive based on LTOtechnology, with microcode, etc., to perform desired operations withrespect to the magnetic tape cartridge 10. In the instant example, themagnetic tape 11 is wound on a reel 13 in the cartridge 10, and, whenloaded in the magnetic tape drive 15, is fed between the cartridge reeland a take up reel 16 in the magnetic tape drive. Alternatively, bothreels of a dual reel cartridge are driven to feed the magnetic tapebetween the reels.

The magnetic tape drive comprises a memory interface 17 for readinginformation from, and writing information to, the cartridge memory 14 ofthe magnetic tape cartridge 10, for example, in a contactless manner. Aread/write system is provided for reading and writing information to themagnetic tape, and, for example, may comprise a read/write and servohead system 18 with a servo system for moving the head laterally of themagnetic tape 11, a read/write servo control 19, and a drive motorsystem 20 which moves the magnetic tape 11 between the cartridge reel 13and the take up reel 16 and across the read/write and servo head system18. The read/write and servo control 19 controls the operation of thedrive motor system 20 to move the magnetic tape 11 across the read/writeand servo head system 18 at a desired velocity, and, in one example,determines the location of the read/write and servo head system withrespect to the magnetic tape 11. In one example, the read/write andservo head system 18 and read/write and servo control 19 employ servosignals on the magnetic tape 11 to determine the location of theread/write and servo head system, and in another example, the read/writeand servo control 19 employs at least one of the reels, such as by meansof a tachometer, to determine the location of the read/write and servohead system with respect to the magnetic tape 11. The read/write andservo head system 18 and read/write and servo control 19 may comprisehardware elements and may comprise any suitable form of logic, includinga processor operated by software, or microcode, or firmware, or maycomprise hardware logic, or a combination.

A control system 24 communicates with the memory interface 17, andcommunicates with the read/write system, e.g., at read/write and servocontrol 19. The control system 24 may comprise any suitable form oflogic, including a processor operated by software, or microcode, orfirmware, or may comprise hardware logic, or a combination.

The illustrated and alternative embodiments of magnetic tape drives areknown to those of skill in the art, including those which employ dualreel cartridges.

The control system 24 typically communicates with one or more hostsystems 25, and operates the magnetic tape drive 15 in accordance withcommands originating at a host. Alternatively, the magnetic tape drive15 may form part of a subsystem, such as a library, and may also receiveand respond to commands from the subsystem.

As illustrated, the magnetic tape drive 15 provides information to thecartridge memory 14 of the magnetic tape cartridge 10, and providesinformation to the magnetic tape 11 of the magnetic tape cartridge 10.

Referring to FIG. 3, a magnetic tape 11 may be organized in many ways.Typically, a magnetic tape is arranged with parallel tracks, and mayalso be arranged with several parallel wraps of groups of paralleltracks. In one example, the magnetic tape is moved longitudinally in afirst direction while the head system reads and/or writes data withrespect to one wrap, and is reversed to be moved in the oppositedirection and the head system is shifted to another wrap.

In FIG. 3, the information is shown laid out as a single wrap for thepurpose of illustration. An area 40 at or near the front end of themagnetic tape 11 is called the “beginning of tape” (BOT) as is known tothose of skill in the art. In a single reel magnetic tape cartridge,this is the area of one or more wraps near the front end of the magnetictape (leader block) that is loaded into the take up reel 16 of themagnetic tape drive 15 as depicted in FIG. 2. In a dual reel magnetictape cartridge, an area of the magnetic tape near the center, abouthalfway between one reel and the other, is typically designated the BOT,and may comprise one or more wraps. Such a dual reel magnetic tapecartridge is also referred to as a midpoint load tape.

Referring to FIG. 3, in one embodiment, the magnetic tape cartridge isconfigured to provide, among the information of the BOT, such asinitialization information 42 and housekeeping information 44, one ormore write once overwrite protection pointers 45 which identify data tobe protected from being overwritten, and thereby allow a rewritablemagnetic tape to be treated as write once.

Also, a magnetic tape typically records data in the form of “data sets”46 or similar arrangements of data. In one example, each complete dataset is accompanied by a “data set information table” 47 which providesinformation about the data set 46. In one embodiment, each data setinformation table 47 provides at least one write once overwriteprotection pointer 49 which identifies data to be protected from beingoverwritten, and thereby allows a rewritable magnetic tape to be treatedas write once. The write once overwrite protection pointers 49 maycomprise an addition to or an alternative to the write once overwriteprotection pointers 45 at the BOT.

Referring to FIG. 4, an example of the content of the cartridge memory14 of the magnetic tape cartridge 10 of FIGS. 1 and 2 is illustrated.One example of a cartridge memory 14 and its content is described inStandard ECMA-319, June 2001, “Data Interchange on 12, 7 mm 384-TrackMagnetic Tape Cartridges—Ultrium-1 Format”, Annex D—LTO CartridgeMemory, pp. 95-115. As one example, the cartridge memory 14 is arrangedin areas of various sizes with information organized into “pages”. Thecartridge memory 14 may be similar to the memory and transponder used in“smart cards” as are known to those of skill in the art. Those of skillin the art may envision additional types of cartridge memories.

Referring to FIG. 4, in one embodiment, information 50 about themagnetic tape cartridge is provided, in addition to WORM information 52.The WORM information may, for example, indicate a level of WORMprotection, any read protection limiting access to the data to be read,etc., and at least one write once overwrite protection pointer 55 whichidentifies data to be protected from being overwritten, and whichthereby allows a rewritable magnetic tape to be treated as write once.

FIG. 5 illustrates an embodiment of a write once overwrite protectionpointer 60 (OPP) which may comprise a magnetic tape overwrite protectionpointer 45 at the BOT of FIG. 3, may comprise a magnetic tape overwriteprotection pointer 49 in a DSIT of FIG. 3, or may comprise a cartridgememory overwrite protection pointer 55 of FIG. 4.

Referring to FIG. 5, an overwrite protection pointer 60 identifies alocation 62. As an example, the identified location may comprise thewrap and the offset from a starting point, such as the number of servotiming or longitudinal distance marks from a starting point. Stillalternatively, the location may be identified by means of a count of thenumber 64 of filemarks recorded to the magnetic tape from the BOT to theidentified location. Alternatively, or additionally, the location may beidentified by means of a count of the number 66 of the records recordedto the magnetic tape from the BOT to the identified location. Thelocation identified by an overwrite protection pointer is the locationbefore which is protected from being overwritten.

If a plurality of overwrite protection pointers 60 are provided, atimestamp 68 may be provided to identify the current valid overwriteprotection pointer. The timestamp may or may not be a direct part of theoverwrite protection pointer, but is associated with the pointer.

Referring to FIGS. 1, 2, 3, 4 and 5, in accordance with an embodiment ofthe present invention, a magnetic tape cartridge 10, a recording system24, 19, 18, and a magnetic tape drive 15 are configured to, for example,guard against tampering with a write once overwrite protection pointerwhich allows a rewritable magnetic tape to be treated as write once. Themagnetic tape 11 is configured to provide at least one overwriteprotection pointer 45, 49, the overwrite protection pointer identifyingdata to be protected from being overwritten; and the cartridge memory 14is configured to provide the at least one overwrite protection pointer55, the overwrite protection pointer identifying magnetic tape data tobe protected from being overwritten. In these embodiments, the presenceof the overwrite protection pointer in both the magnetic tape 11 and thecartridge memory 14 guards against tampering.

Alternatively, or additionally, the presence of the overwrite protectionpointers 45, 49 at two separate areas of the magnetic tape 11 guardsagainst tampering.

Referring to FIGS. 3 and 4, in another embodiment of the presentinvention, the magnetic tape overwrite protection pointer 45 and/or 49,and/or the cartridge memory overwrite protection pointer 55, comprises aplurality of updateable overwrite protection pointers, the overwriteprotection pointers configured to be updated in a sequence. In oneexample, the sequence is in a circular order, e.g. OPP#0, OPP#1, OPP#2,OPP#3, OPP#0, . . . In one example, the sequentially updated overwriteprotection pointers preserve the lifecycle of a cartridge memory.

In an alternative embodiment, a plurality of updateable magnetic tapeoverwrite protection pointers 45 and/or 49 may be updated in a sequence(with or without overwrite protection pointers in the cartridge memory);and in a further alternative embodiment, a plurality of updateablecartridge memory overwrite protection pointers 55 may be updated in asequence (with or without magnetic tape overwrite protection pointers).

Referring to FIG. 5, in further embodiments, the magnetic tape and/orthe cartridge memory updateable overwrite protection pointers 60 areconfigured to be time-stamped 68 when updated, to identify the currentvalid overwrite protection pointer, as discussed above. The time stampmay be an indication of the number of times that the magnetic tapecartridge has been loaded to a magnetic tape drive, or may be a clocktime of a subsystem in which the magnetic tape drive is located, forexample, a library.

Alternatively, the overwrite protection pointers 60 may be arranged in asequence, for example, of an ever increasing location value, in that nopreviously protected area is later “unprotected”. As the result, thenewest OPP is always an increased value, and the highest value is bynature the latest. In this sense, the location value of the OPP may beconsidered the equivalent of “timestamp”.

Alternatively, referring to FIG. 5, the count of the number 64 offilemarks recorded to the magnetic tape from the BOT to the identifiedlocation, and/or the count of the number 66 of the records recorded tothe magnetic tape from the BOT to the identified location may comprisetimestamps. Those of skill in the art can envision additional time stampembodiments.

In still further embodiments, additionally or alternatively, themagnetic tape and/or the cartridge memory updateable overwriteprotection pointers are configured to duplicate the current validoverwrite protection pointer to identify the current valid overwriteprotection pointer. Referring to FIGS. 3 and 4, the current validoverwrite protection pointer may comprise OPP#1, and be designated asthe current valid overwrite protection pointer by having the pointerduplicated as OPP#2. The duplication may be accomplished upon receipt ofan unload request by the magnetic tape drive 15 of FIG. 2. As anexample, if OPP#1 is written after a string of user data is written, andthen an unload request is received, the contents of OPP#1 is copied toOPP#2.

When a new cartridge is loaded, the magnetic tape drive 15 recordingsystem 24, 19, 18 of FIG. 2 determines the latest overwrite protectionpointer by means of the timestamps as discussed above. It should havethe latest timestamp or be tied with the latest timestamp. The secondcopy is verified as well. The second copy is then overwritten when thefirst OPP update occurs on the new load. In the above example, the firstupdate would be to OPP#2, because it is the second copy of the previousfinal OPP.

If a duplicate OPP is not found which matches the OPP with the latesttimestamp, then another set of the OPP's is consulted to provide OPPintegrity. For example, referring to FIGS. 3 and 4, if OPP#2 does notagree with OPP#1 of the OPP's 45 in the BOT, then OPP#1 and OPP#2 of theOPP's 55 of the cartridge memory are consulted. In another example, ifOPP#2 does not agree with OPP#1 of the OPP's 45 in the BOT, then OPP#1and OPP#2 of the OPP's 49 of the DSIT at the expected end of data (EOD)are consulted.

Integrity of the overwrite protection pointer may be provided byarranging the overwrite protection pointers in a sequence, for example,of an ever increasing value, as discussed above. Thus, the highestlocation value OPP is by nature the latest.

Additional integrity checks may be made to insure that an OPP is alwaysgreater or equal to any logically preceding OPP's, and existing OPP's,for example, in the DSIT's, are less than or equal to “current” OPP'sfrom the cartridge memory. As such, the OPP integrity is maintained inthe absence of, or in addition to, timestamps.

Thus, in a further embodiment of the present invention, the overwriteprotection pointers are read and compared to check for validity and, ifvalidity is not insured, i.e. the cartridge memory and tape OPP's do notmatch, there is no duplicate OPP or the last OPP does not have thelatest timestamp or does not have the greatest value, then the cartridgewill be treated as lacking OPP integrity. For example, the tape could betreated as read only, or treated as a “tampered” tape and disallowedfrom all read and/or write processing. Alternatively, data could beappended only at the logical end of tape. The selection of these orother options may be arbitrary or based on information found by thevarious OPP methods.

Referring to FIGS. 2, 3, 4 and 5, control 24, in one embodiment, isconfigured to operate the recording channel 18, 19 to read at least oneOPP from magnetic tape 11, and to operate the memory interface 17 toread at least one OPP from cartridge memory 14. In another embodiment, aplurality of overwrite protection pointers are read from the magnetictape 11. The logic then determines from the read overwrite protectionpointers, e.g. by comparing at least two of the read OPP's, the validityof the OPP's.

Another method of assuring integrity of the overwrite protectionpointers is to interlock the OPP's with “good status” which is returnedto the application which wrote the record or File Mark which caused theOPP to be advanced.

In an additional embodiment of the present invention, the sequence ofupdating the overwrite protection pointers may be to update the pointers49 of the DSIT of the last data set written when an unload command isreceived by the magnetic tape drive, called the end of data (EOD) dataset, the pointers 55 of the cartridge memory are then updated, and,lastly, the contents of the cartridge memory WORM information is copiedto the housekeeping section of the BOT, thereby providing the updatedpointers 45.

In a further embodiment of the present invention, the overwriteprotection pointers may identify locations that are at the end ofcompleted data that has been written, in order to allow an applicationto overwrite incomplete constructs and change or update labels, such asto update or invalidate information.

In another embodiment of the present invention, the overwrite protectionpointers may identify locations that are at the end of data, prior tothe end of file or similar constructs, to allow an application to appenddata to what had been an end of data or end of file.

Referring to FIG. 6, the information is shown laid out as a single wrapof magnetic tape 11 for the purpose of illustration. Typical constructsinclude a label 70 at a beginning of a partition, and header 71 at thebeginning, for example, of a file, followed by user data 73. A trailer75, such as at the end of a user file, may indicate the end of a fileand, for example, comprise a filemark 76, a first end of file indicator77, a second end of file indicator 78, and another filemark 79.

In the example of FIG. 6, the overwrite protection pointer 60 of FIG. 5thus is configured to identify the location 80 of FIG. 6, at the end ofthe user data 73 and prior to the end of file constructs of trailer 75.Similarly, the OPP does not identify a header 71, but rather is movedwith the data. Those of skill in the art will envision similar locationsin similar constructs.

Thus, the application can go back and forth and change candidateconstructs and the OPP will identify the data after it is completely andfinally written by the application. For example, the DSIT having theupdated OPP (or OPP's) will be the end of data (EOD) data set.

Those of skill in the art will understand that changes may be made withrespect to the number or content of the OPP's and to their locations.Further, those of skill in the art will understand that differingspecific component arrangements may be employed than those illustratedherein.

While the preferred embodiments of the present invention have beenillustrated in detail, it should be apparent that modifications andadaptations to those embodiments may occur to one skilled in the artwithout departing from the scope of the present invention as set forthin the following claims.

1. A magnetic tape cartridge comprising: a magnetic tape configured toprovide at least one overwrite protection pointer, said overwriteprotection pointer identifying data to be protected from beingoverwritten; and a cartridge memory configured to provide said at leastone overwrite protection pointer, said overwrite protection pointeridentifying magnetic tape data to be protected from being overwritten.2. The magnetic tape cartridge of claim 1, wherein said magnetic tape atleast one overwrite protection pointer and said cartridge memory atleast one overwrite protection pointer, comprises a plurality ofupdateable overwrite protection pointers, said overwrite protectionpointers configured to be updated in a sequence.
 3. The magnetic tapecartridge of claim 2, wherein said magnetic tape and said cartridgememory updateable overwrite protection pointers are configured to betime-stamped when updated, to identify the current valid overwriteprotection pointer.
 4. The magnetic tape cartridge of claim 2, whereinsaid magnetic tape and said cartridge memory updateable overwriteprotection pointers are configured to duplicate the current validoverwrite protection pointer to identify the current valid overwriteprotection pointer.
 5. The magnetic tape cartridge of claim 1, whereinsaid magnetic tape at least one overwrite protection pointer and saidcartridge memory at least one overwrite protection pointer areconfigured to identify the end of data that is to be protected frombeing overwritten, prior to end of file constructs.
 6. The magnetic tapecartridge of claim 1, wherein said magnetic tape is configured toprovide said at least one overwrite protection pointer as at least apart of “beginning of tape” information.
 7. The magnetic tape cartridgeof claim 1, wherein said magnetic tape is configured to provide said atleast one overwrite protection pointer as at least a part of “data setinformation table”.
 8. The magnetic tape cartridge of claim 1, whereinsaid magnetic tape is configured to provide a copy of said at least onecartridge memory overwrite protection pointer to a “housekeeping dataset” of said magnetic tape.
 9. A recording system for magnetic tape,said magnetic tape mounted with respect to a magnetic tape cartridgehaving a cartridge memory, comprising: logic configured to record atleast one overwrite protection pointer on said magnetic tape, saidoverwrite protection pointer identifying data to be protected from beingoverwritten; and logic configured to provide said at least one overwriteprotection pointer to said cartridge memory. said overwrite protectionpointer identifying magnetic tape data to be protected from beingoverwritten.
 10. The recording system of claim 9, wherein: said logicconfigured to record at least one overwrite protection pointer on saidmagnetic tape and said logic configured to provide said at least oneoverwrite protection pointer to said cartridge memory, are configured toprovide a plurality of updateable overwrite protection pointers, saidoverwrite protection pointers configured to be updated in a sequence.11. The recording system of claim 10, wherein: said logic configured torecord at least one overwrite protection pointer on said magnetic tapeand said logic configured to provide said at least one overwriteprotection pointer to said cartridge memory, are configured totime-stamp said magnetic tape and said cartridge memory updateableoverwrite protection pointers when updated, to identify the currentvalid overwrite protection pointer.
 12. The recording system of claim10, wherein: said logic configured to record at least one overwriteprotection pointer on said magnetic tape and said logic configured toprovide said at least one overwrite protection pointer to said cartridgememory, are configured to duplicate the current valid said magnetic tapeand said cartridge memory updateable overwrite protection pointers, toidentify the current valid overwrite protection pointer.
 13. Therecording system of claim 9, wherein: said logic configured to record atleast one overwrite protection pointer on said magnetic tape and saidlogic configured to provide said at least one overwrite protectionpointer to said cartridge memory, are configured to provide saidoverwrite protection pointers, identifying the end of data that is to beprotected from being overwritten, prior to end of file constructs. 14.The recording system of claim 9, wherein said logic configured to recordat least one overwrite protection pointer on said magnetic tape isconfigured to provide said at least one overwrite protection pointer asat least a part of “beginning of tape” information.
 15. The recordingsystem of claim 9, wherein said logic configured to record at least oneoverwrite protection pointer on said magnetic tape is configured toprovide said at least one overwrite protection pointer as at least apart of “data set information table”.
 16. The recording system of claim9, additionally comprising: logic configured to provide a copy of saidat least one cartridge memory overwrite protection pointer to a“housekeeping data set” of said magnetic tape.
 17. A magnetic tape driveconfigured to read and write information with respect to a magneticrape, said magnetic tape mounted with respect to a magnetic tapecartridge having a cartridge memory, comprising: at least one motorconfigured to move said magnetic tape longitudinally; at least oneread/write, head configured to read from and to write to said magnetictape while said magnetic tape is moved longitudinally by said at leastone motor; at least one recording channel configured to operate said atleast one read/write head to read from and to write to said magnetictape; a memory interface configured to communicate with respect to saidcartridge memory; and at least one control system configured to operatesaid at least one recording channel to record at least one overwriteprotection pointer on said magnetic tape, said overwrite protectionpointer identifying data to be protected from being overwritten; andconfigured to operate said memory interface to provide said at least oneoverwrite protection pointer to said cartridge memory, said overwriteprotection pointer identifying magnetic tape data to be protected frombeing overwritten.
 18. The magnetic tape drive of claim 17, wherein:said at least one control system is configured to provide a plurality ofsaid magnetic tape and said cartridge memory updateable overwriteprotection pointers, said overwrite protection pointers configured to beupdated in a sequence.
 19. The magnetic tape drive of claim 18, wherein:said at least one control system is configured to time-stamp saidmagnetic tape and said cartridge memory updateable overwrite protectionpointers when updated, to identify the current valid overwriteprotection pointer.
 20. The magnetic tape drive of claim 18, wherein:said at least one control system is configured to duplicate the currentvalid said magnetic tape and said cartridge memory updateable overwriteprotection pointers, to identify the current valid overwrite protectionpointer.
 21. The magnetic tape drive of claim 17, wherein: said at leastone control system is configured to provide said overwrite protectionpointers, identifying the end of data that is to be protected from beingoverwritten, prior to end of file constructs.
 22. The magnetic tapedrive of claim 17, wherein said at least one control system isconfigured to provide said at least one overwrite protection pointer forsaid magnetic tape as at least a part of “beginning of tape”information.
 23. The magnetic tape drive of claim 17, wherein said atleast one control system is configured to provide said at least oneoverwrite protection pointer as at least a part of “data set informationtable”.
 24. The magnetic tape drive of claim 17, wherein said at leastone control system is configured to provide a copy of said at least onecartridge memory overwrite protection pointer to a “housekeeping dataset” of said magnetic tape.
 25. A recording system for magnetic tape,said magnetic tape mounted with respect to a magnetic tape cartridge,comprising: logic configured to compare a plurality of overwriteprotection pointers of said magnetic tape cartridge, at least one saidoverwrite protection pointer read from said magnetic tape; and logicconfigured to determine from said comparison the validity of saidoverwrite protection pointers, wherein said magnetic tape cartridgecomprises a cartridge memory; and said logic configured to compare, isconfigured to compare at least one said overwrite protection pointerread from said magnetic tape and at least one said overwrite protectionpointer read from said cartridge memory.
 26. A magnetic tape driveconfigured to read and write information with respect to a magnetictape, said magnetic tape mounted with respect to a magnetic tapecartridge having a cartridge memory, comprising: at least one motorconfigured to move said magnetic tape longitudinally; at least oneread/write head configured to read from and to write to said magnetictape while said magnetic tape is moved longitudinally by said at leastone motor; at least one recording channel configured to operate said atleast one read/write head to read from and to write to said magnetictape; a memory interface configured to communicate with respect to saidcartridge memory; and at least one control system configured to operatesaid at least one recording channel to read at least one overwriteprotection pointer recorded on said magnetic tape, said overwriteprotection pointer identifying data to be protected from beingoverwritten; and configured to operate said memory interface to read atleast one overwrite protection pointer of said cartridge memory, saidoverwrite protection pointer identifying magnetic tape data to beprotected from being overwritten; and configured to determine from saidread overwrite protection pointers, the validity of said overwriteprotection pointers.